The invention relates to a device for welding cylinder-shaped elements and rotatable bodies together, comprising an electrode shaft, positioning and fastening means for the elements to be welded together and a pipe shaft surrounding the electrode shaft.
When welding cylinder-shaped workpieces together, the connecting surfaces are of two shapes as a rule. With cylinder-shaped workpieces which are cut transversely in respect to the cylinder axis, the ends meet squarely and the joint surface constitutes a circle. This type of welded connection is a rotatable welded connection, which can be easily mechanized. If the cylinders meet at a defined angle, a geometric figure is formed at the joint surface, whose shape is a function of the diameters of the cylinders and of the angle, at which the center lines of the cylinders meet.
If there are several of these branched cylinders, i.e. pipe junctions, on a base cylinder, which in addition also lie close together, the customary welding from the outside is difficult. Such structures can be, for example, housings of multiway valves, filter bodies, pipe junctions and corresponding structural elements. When welding pipe junctions, and in particular T-junctions, the small height of the neck of the base cylinder and the size of customary welding nozzles present problems.
The above mentioned problems can be eliminated by approaching the welding position from the inside of the junction cylinder. Then the small height of the neck or a second junction in the vicinity on the outside no longer constitute obstacles. The welding nozzle is at the height of the seam, while the workpiece (or the welding nozzle) turns around its own axis.
A second area of problems is constituted by long workpieces, whose rotation cannot be simply provided. A typical example of this is if distribution chambers are to be made from a pipe, wherein several pipe junctions are attached to a long pipe.
The coaxial alignment of the cylinders in respect to each other is of extreme importance. To assure the quality of the weld seam, it is necessary to protect the workpieces to be welded together from the oxygen in the air by enclosing the workpieces in a chamber filled with a protective gas. In order to minimize the amount of the protective gas and the fill time, the chamber must be as small as possible. However, the small size of the chamber in turn causes problems when inserting the workpiece in the holder located in the chamber. Because of the small size of the chamber it is not possible to simultaneously work with one""s hands in the chamber and to look into the chamber.
The object of the invention is based on providing a device by means of which the above described problems can be removed and the consumption of protective gas in particular can be reduced, even if the size of the workpieces to be welded together varies.
The invention relates to a device for welding cylinder-shaped and rotatable elements together. An axially displaceable electrode shaft is provided in a rotatably seated pipe shaft. The pipe shaft can be rotated with respect to the electrode shaft, and a connecting head is provided on one end of the pipe shaft, which is equipped with gripper elements for an interchangeable protective chamber. Gripper and positioning elements for a fastening cassette provided for the parts to be welded together, which is also interchangeable, are arranged in the protective chamber. The electrode shaft extends through the connecting head into the protective chamber.
An exemplary embodiment of the invention will be explained in greater detail in what follows, making reference to the attached drawings.